Actuators for control valves and shut-off devices have hitherto been operated almost exclusively pneumatically or by means of electric motors, i.e., they have been provided with pneumatic drive units or with electric motors. There are electromagnetic actuators, which have an actuating element, which can be brought into a plurality of rotated positions and which can be adjusted by a plurality of differently positioned coils (DE 2004 037 360 A1, DE 10 2005 026 535 A1). While the control means are relatively simple in pneumatic drive units, they do require the presence of a compressed air source, electric motor drives usually require expensive motor control means and amplifier means and optionally additional gear means. In addition, the working torques that can be attained are low in case of small overall dimensions.
It is generally known that such solenoid plunger units or moving coils of the type mentioned in the introduction are able to generate strong actuating forces even in case of very small size, so that they are also suitable for reliably actuating closing elements of valves by air pressure or on-off devices between two defined end positions and to guarantee at the same time the two end positions of the respective actively moving parts as safety positions without additional auxiliary forces with special energy supply being necessary when the necessary electrical energy, more precisely, the sufficient amperage is present in a correspondingly oversized manner. Aside from the fact that no defined intermediate positions located between the two end positions can be set for the closing elements actuated by the solenoid plunger magnets in the case of the prior-art solenoid plunger magnets, these closing elements are always actuated with the same actuating signal and with the same operating voltage and with the same work output, i.e., with the same energy consumption.